How to add weight to your textures
First, let me explain what the different texture images are:

Diffuse - A normal picture of the material
Albedo - The color of the material (diffuse minus shadows)
Ambient Occlusion (or just AO) - The shadows of the material
Displacement - A depth map of the material (white = high, dark = low)
Normal - Which way the each point on the surface is facing (next to diffuse/albedo, this is probably the most important)
Roughness - How rough each point on the surface is
Glossiness - How glossy each point on the surface is (this is literally just the inverse of roughness.  You only need one)

Here's how you can connect each of them to the Principled Shader:

In that example, I'm using the albedo texture for the base color.  Here's a comparison using the albedo texture, diffuse texture, and albedo along with the ambient occlusion.
Albedo:

Diffuse:

Albedo + Ambient Occlusion:

(Note, you can probably get the colors to match the previous two better if you use something like the color ramp node between the Ambient Occlusion texture and the mix color node)
For the normal texture, you need to use the Normal Map node.  For only the displacement texture, use just the Bump node.  For both textures, use both nodes as I showed in the example.